.container{
  width: 1200px;
  margin: 50px auto;
  .course-tab{
    width: 1200px;
    height: 52px;
    background-color: #f5f5f5;
    border: 1px solid #eee;
    margin-bottom: 20px;
    padding-left: 30px;
    box-sizing: border-box;
  }
}